1. Field of Invention
This invention is directed generally to bearing assemblies, and more particularly to a vented bearing end cap adapted for attachment to a bearing assembly mounted to a rotating shaft.
2. Background of the Invention
For years, bearing assemblies have been used on rotating shafts. For example, in automated conveyor lines, bearing assemblies are mounted to rotating shafts. In many applications, the bearing assemblies are subjected to harsh operating conditions involving liquid, gaseous, and solid contaminants. The field of beverage bottling presents one particularly harsh environment. Bearings are subjected to spilled juices such as orange and grape juice, and acidic lemonade. Sports drinks, beer, ginger ale, and cola also represent harmful contaminants that may come in contact with the bearing and reduce bearing life. Other packaging and handling environments also subject bearing assemblies to potentially caustic materials. In these applications, it is very important for the lines to continue running, without unscheduled downtime. A bearing failure can result in shutting an entire line down while repairs or replacement bearings are provided. Such costly downtime is to be avoided at all costs.
Consequently, efforts have been made to provide corrosion resistant bearings and bearing assemblies that include various, and oftentimes, intricate sealing arrangements. One such line of bearings is the SEALMASTER(copyright) Gold Line Corrosion Resistant Bearings that are specially designed and manufactured for abrasive and wet environments. In addition, bearing end caps have been provided at the end of a rotating shaft to provide an additional line of defense against harmful contaminants and potentially corrosive materials. One such bearing end cap has been provided in the form of a stainless steel end cap that is typically bolted to the bearing housing. As an alternative to a bolted mounting, the end cap can be provided with exterior retention snaps that snap fit into a corresponding groove in the housing to mount the end cap to the bearing housing. The end cap may be either closed, where the end of the rotating shaft is positioned inside the end cap, or it may be open, where the rotating shaft is allowed to pass the through the end cap. The use of bearing end caps in such situations has provided an added measure of protection to keep contaminants out of the bearing. However, the use of such an end cap presents additional difficulties. For example, in many operating environments, it is common to periodically wash down the equipment with hot water or cleaning solutions under high pressure. Typical wash down protocols use a 1500 p.s.i. rinse at 170 to 180 degrees using hot water or low PH rinse or bleach. The rinse has a tendency to penetrate any seal between the end cap and the bearing housing to which it is mounted. Thus, the end cap may actually trap water, and its accompanying contaminants, between the end cap and the bearing itself. This is not an ideal situation because the contaminants may work their way into the seal creating reduced bearing effectiveness and bearing life. Moreover, the rotating shafts and bearings often operate under heated working conditions. Upon cool down, condensation may occur causing a pooling of water within the end cap.
Accordingly, it has been found that a hole or vent in the underside of the end cap can be used to provide an exit path for any water that enters the end cap during washdown or that forms from condensation during a cool down period. In addition, such a vent serves as a pressure relief for any pressure buildup that occurs during the high pressure washdowns. However, the use of a vent presents additional considerations as well. For example, the use of a vent may allow the rinse to enter the end cap through the vent during washdown, and thus allow undesirable contaminants to come in closer proximity to the bearing. Consequently, there is a need to provide an end cap having a vent that can provide an exit pathway for any trapped water within the end cap, yet also prevent water from entering the endcap during washdown.
The present invention is specifically directed to a bearing end cap adapted for mounting to a bearing housing. In the disclosed embodiment, the end cap is provided with a shroud that extends outwardly from the exterior surface of the sidewall of the end cap and generally encircles a hole or drain that vents the inside of the end cap. The shroud serves to shield the vent and prevent water from entering the end cap during washdown measures. Collectively, the shroud and vent are termed a directional vent.
In a preferred embodiment, the end cap is injection molded and the shroud is integrally molded with the end cap. In addition, although the vent or drain can then be quickly drilled or punched through in a simple secondary operation after the injection molding process is complete, ideally the vent is directly molded into the end cap during the initial injection molding process using a side action, wherein a movable pin within the mold actually forms the vent. Thus, the end cap can be made in a single injection molding process. The geometry of the shroud can consist of any geometry suitable to shield the vent. However, preferably the shroud is generally semicircular, having a break therein facing the open end of the end cap that abuts the bearing housing when mounted. Thus, the vent is positioned between the housing and the generally semicircular shroud when the end cap is mounted to the housing. This positioning of the shroud serves to block and deflect rinse water that is sprayed towards the end cap and housing during wash down. In addition, with the end cap mounted to a circular groove of the housing using retention snaps, the end cap can be rotated about the circular groove. Typically, the end cap is mounted such that the vent is positioned at the lowest point of the end cap relative to the housing. This allows the vent to drain any water or condensation accumulated within the end cap. However, during washdown, the end cap can be rotated 180 degrees to position the vent at the highest point of the end cap relative to the housing. This allows the vent to be further insulated from the wash down rinse, wherein the end cap itself serves to block the incoming rinse. Alternatively, the end cap can be rotated to any position to position the vent away from the direction of the rinse.